644904368 has 40 divisors (see below), whose sum is σ = 1281205200. Its totient is φ = 314302464.

The previous prime is 644904329. The next prime is 644904373. The reversal of 644904368 is 863409446.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 638648 + ... + 639656.

It is an arithmetic number, because the mean of its divisors is an integer number (32030130).

Almost surely, 2^644904368 is an apocalyptic number.

It is an amenable number.

644904368 is a deficient number, since it is larger than the sum of its proper divisors (636300832).

644904368 is a wasteful number, since it uses less digits than its factorization.

644904368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1989 (or 1983 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 44.

The square root of 644904368 is about 25394.9673754467. The cubic root of 644904368 is about 863.9695562547.

The spelling of 644904368 in words is "six hundred forty-four million, nine hundred four thousand, three hundred sixty-eight".